1. Field of the Invention
The present invention relates to a heel unit for a touring binding of a sliding board, comprising a binding body on which two coupling projections for connection to a heel portion of a touring boot are movably held.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Heel units of this type have become widespread, particularly in the sport of ski touring, to fix the heel of a touring boot to a sliding board (touring ski, splitboard or similar) in that the coupling projections formed on the front ends of two coupling pins engage in associated recesses on the heel of the ski boot.
Examples of heel units of the aforementioned type are disclosed in EP 0 199 098 A2 and in AT 402 020 B. The known bindings each use two coupling pins which are held on a housing of the heel unit in such a way that they run parallel to each other and protrude towards the touring boot. Moreover, the pins are movable in relation to each other in a plane parallel to a sliding board plane (in the horizontal plane) while overcoming a restoring force in order to provide a release mechanism for release in the event of a forward fall. Release of the known heel unit on a touring boot will be described below in greater detail with reference to FIG. 1.
FIG. 1 shows a touring boot 100 in a view from behind (along the longitudinal axis of the sliding board running in the X direction). The sectional diagram of FIG. 1 illustrates a heel portion 110 of touring boot 100. Also indicated are two coupling pins 120 which protrude from the heel unit (not shown) in the X direction and engage in recesses 122 of touring boot 100. The inner margins of recesses 122 each comprise opening portions 124 at which recesses 122 are open towards a sole surface 126 of boot 100, release projections 128 which protrude away from the middle of the boot in a Y direction (perpendicular to a vertical Z direction and perpendicular to the X direction), latching portions 130 in the shape of notches into which coupling pins 120 may engage, and upper contact surfaces 132 which run essentially in the Y direction.
In the position shown in FIG. 1, coupling pins 120 are preloaded and can be moved out of this position in a horizontal plane (Y direction) away from each other by means of an elastic device (not shown) of the heel unit. In the position shown in FIG. 1, coupling pins 120 are in engagement with the notches of latching portions 130 and touring boot 100 is secured on the heel unit (downhill position).
It can also be seen in FIG. 1 that the inner margin of recesses 122 additionally has insertion contours 134 in relation to the Z-axis between release projections 128 and opening portions 124. The gap between both insertion contours 134 of both recesses 122 enlarges with increasing distance from sole 126 of touring boot 100. This makes it possible when stepping into the touring binding of touring boot 100 to approach coupling pins 120 from above in such a way that coupling pins 120 enter opening portions 124 via sole 126 and on further lowering of heel portion 110 they are spread apart by insertion contours 134 against the action of the elastic device of the heel unit. After further downward motion of heel portion 110 by overcoming the force of the elastic device, coupling pins 120 pass release projections 128 until they engage in the notches of latching portions 130. The touring boot is then in the normal position (downhill position) with the heel unit coupled.
In the event of an My-release, in which a torque acts on touring boot 100 about an axis running in the Y direction such that heel portion 110 is moved upwards in the direction of arrow A in FIG. 1, and with a force that exceeds a predetermined release force (e.g. during a fall), coupling pins 120 are forced sideways by release projections 128 out of their position shown in FIG. 1 such that they move apart from each other in the horizontal plane. As soon as heel portion 110 moves upwards in such a way that release projections 128 are disposed above the middle, measured in the Z direction, of coupling pins 120, touring boot 100 may be moved further upwards in the direction of arrow A without further exertion of force whereupon coupling pins 120 slip off release projections 128 until they exit from opening portions 124 on sole 126 of touring boot 100. The touring boot is then released and disengaged from the ski (at least in the heel region).
When the touring binding is loaded, e.g. during downhill travel, the decision is made as to whether or not the heel unit will release, i.e. whether or not coupling pins 120 will exit recesses 122, within the short distance between the position of coupling pins 120 inside latching portions 130 shown in FIG. 1 and the point at which release projections 128 are passed. Particularly with a sporty skiing style (e.g. in competitive sport), relatively high forces may act momentarily on the sliding board when travelling over obstacles, uneven ground or during brief collisions with rocks or similar on the ski slope. An abrupt, brief load which may temporarily be large enough to overcome the release force for spreading apart coupling pins 120 then acts between touring boot 100 and the heel unit. The coupling pins therefore tend to overcome release projections 128 even in the case of a brief impact or shock such that the touring boot is released from the heel unit although this temporary disruptive event is not yet connected to a fall by the skier. The known binding therefore leads in some cases, particularly with a sporty skiing style, to an undesirable inadvertent release.